* Copyright 1999, 2000, 2001, 2008 Bernie Innocenti <bernie@codewiz.org>
* -->
*
- * \brief Process scheduler (public interface).
+ * \brief BeRTOS Kernel core (Process scheduler).
*
* \version $Id$
* \author Bernie Innocenti <bernie@codewiz.org>
+ *
+ * $WIZ$ module_name = "kernel"
+ * $WIZ$ module_configuration = "bertos/cfg/cfg_proc.h"
+ * $WIZ$ module_depends = "switch_ctx"
+ * $WIZ$ module_supports = "not atmega103"
*/
+
#ifndef KERN_PROC_H
#define KERN_PROC_H
-#include "cfg/cfg_kern.h"
-#include <cfg/compiler.h>
+#include "cfg/cfg_proc.h"
+#include "cfg/cfg_signal.h"
+#include "cfg/cfg_monitor.h"
-#if CONFIG_KERN_PREEMPT
- #include <cfg/debug.h> // ASSERT()
-#endif
+#include <struct/list.h> // Node, PriNode
+
+#include <cfg/compiler.h>
+#include <cfg/debug.h> // ASSERT()
-#include <cpu/types.h> // cpustack_t
+#include <cpu/types.h> // cpu_stack_t
+#include <cpu/frame.h> // CPU_SAVED_REGS_CNT
/*
- * Forward declaration. The definition of struct Process is private to the
- * scheduler and hidden in proc_p.h.
+ * WARNING: struct Process is considered private, so its definition can change any time
+ * without notice. DO NOT RELY on any field defined here, use only the interface
+ * functions below.
+ *
+ * You have been warned.
*/
-struct Process;
+typedef struct Process
+{
+#if CONFIG_KERN_PRI
+ PriNode link; /**< Link Process into scheduler lists */
+#else
+ Node link; /**< Link Process into scheduler lists */
+#endif
+ cpu_stack_t *stack; /**< Per-process SP */
+ iptr_t user_data; /**< Custom data passed to the process */
+
+#if CONFIG_KERN_SIGNALS
+ sigmask_t sig_wait; /**< Signals the process is waiting for */
+ sigmask_t sig_recv; /**< Received signals */
+#endif
-/* Task scheduling services */
+#if CONFIG_KERN_HEAP
+ uint16_t flags; /**< Flags */
+#endif
+
+#if CONFIG_KERN_HEAP | CONFIG_KERN_MONITOR
+ cpu_stack_t *stack_base; /**< Base of process stack */
+ size_t stack_size; /**< Size of process stack */
+#endif
+
+ /* The actual process entry point */
+ void (*user_entry)(void);
+
+#if CONFIG_KERN_MONITOR
+ struct ProcMonitor
+ {
+ Node link;
+ const char *name;
+ } monitor;
+#endif
+
+} Process;
+
+/**
+ * Initialize the process subsystem (kernel).
+ * It must be called before using any process related function.
+ */
void proc_init(void);
-struct Process *proc_new_with_name(const char* name, void (*entry)(void), iptr_t data, size_t stacksize, cpustack_t *stack);
+
+struct Process *proc_new_with_name(const char *name, void (*entry)(void), iptr_t data, size_t stacksize, cpu_stack_t *stack);
#if !CONFIG_KERN_MONITOR
+ /**
+ * Create a new named process and schedules it for execution.
+ *
+ * When defining the stacksize take into account that you may want at least:
+ * \li save all the registers for each nested function call;
+ * \li have memory for the struct Process, which is positioned at the bottom
+ * of the stack;
+ * \li have some memory for temporary variables inside called functions.
+ *
+ * The value given by KERN_MINSTACKSIZE is rather safe to use in the first place.
+ *
+ * \param entry Function that the process will execute.
+ * \param data Pointer to user data.
+ * \param size Length of the stack.
+ * \param stack Pointer to the memory area to be used as a stack.
+ *
+ * \return Process structure of new created process
+ * if successful, NULL otherwise.
+ */
#define proc_new(entry,data,size,stack) proc_new_with_name(NULL,(entry),(data),(size),(stack))
#else
#define proc_new(entry,data,size,stack) proc_new_with_name(#entry,(entry),(data),(size),(stack))
#endif
+/**
+ * Terminate the execution of the current process.
+ */
void proc_exit(void);
+
+/**
+ * Public scheduling class methods.
+ */
void proc_yield(void);
-#define proc_switch proc_yield /* OBSOLETE */
-int proc_testSetup(void);
-int proc_testRun(void);
-int proc_testTearDown(void);
+#if CONFIG_KERN_PREEMPT
+bool proc_needPreempt(void);
+void proc_preempt(void);
+#else
+INLINE bool proc_needPreempt(void)
+{
+ return false;
+}
+
+INLINE void proc_preempt(void)
+{
+}
+#endif
-struct Process *proc_current(void);
-iptr_t proc_currentUserData(void);
void proc_rename(struct Process *proc, const char *name);
const char *proc_name(struct Process *proc);
const char *proc_currentName(void);
-#if CONFIG_KERN_PRI
-void proc_setPri(struct Process *proc, int pri);
-#endif
-
/**
- * Disable preemptive task switching.
- *
- * The scheduler maintains a global nesting counter. Task switching is
- * effectively re-enabled only when the number of calls to proc_permit()
- * matches the number of calls to proc_forbid().
- *
- * \note Calling functions that could sleep while task switching is disabled
- * is dangerous and unsupported.
+ * Return a pointer to the user data of the current process.
*
- * \note proc_permit() expands inline to 1-2 asm instructions, so it's a
- * very efficient locking primitive in simple but performance-critical
- * situations. In all other cases, semaphores offer a more flexible and
- * fine-grained locking primitive.
- *
- * \sa proc_permit()
+ * To obtain user data, just call this function inside the process. Remember to cast
+ * the returned pointer to the correct type.
+ * \return Pointer to the user data of the current process.
*/
-INLINE void proc_forbid(void)
+INLINE iptr_t proc_currentUserData(void)
{
- #if CONFIG_KERN_PREEMPT
- // No need to protect against interrupts here.
- extern int preempt_forbid_cnt;
- ++preempt_forbid_cnt;
-
- /*
- * Make sure preempt_forbid_cnt is flushed to memory so the
- * preemption softirq will see the correct value from now on.
- */
- MEMORY_BARRIER;
- #endif
+ extern struct Process *current_process;
+ return current_process->user_data;
}
+int proc_testSetup(void);
+int proc_testRun(void);
+int proc_testTearDown(void);
+
/**
- * Re-enable preemptive task switching.
+ * Return the context structure of the currently running process.
*
- * \sa proc_forbid()
+ * The details of the Process structure are private to the scheduler.
+ * The address returned by this function is an opaque pointer that can
+ * be passed as an argument to other process-related functions.
*/
-INLINE void proc_permit(void)
+INLINE struct Process *proc_current(void)
{
- #if CONFIG_KERN_PREEMPT
+ extern struct Process *current_process;
+ return current_process;
+}
+
+#if CONFIG_KERN_PRI
+ void proc_setPri(struct Process *proc, int pri);
+#else
+ INLINE void proc_setPri(UNUSED_ARG(struct Process *,proc), UNUSED_ARG(int, pri))
+ {
+ }
+#endif
+
+#if CONFIG_KERN_PREEMPT
+
+ /**
+ * Disable preemptive task switching.
+ *
+ * The scheduler maintains a global nesting counter. Task switching is
+ * effectively re-enabled only when the number of calls to proc_permit()
+ * matches the number of calls to proc_forbid().
+ *
+ * \note Calling functions that could sleep while task switching is disabled
+ * is dangerous and unsupported.
+ *
+ * \note proc_permit() expands inline to 1-2 asm instructions, so it's a
+ * very efficient locking primitive in simple but performance-critical
+ * situations. In all other cases, semaphores offer a more flexible and
+ * fine-grained locking primitive.
+ *
+ * \sa proc_permit()
+ */
+ INLINE void proc_forbid(void)
+ {
+ extern cpu_atomic_t preempt_count;
+ /*
+ * We don't need to protect the counter against other processes.
+ * The reason why is a bit subtle.
+ *
+ * If a process gets here, preempt_forbid_cnt can be either 0,
+ * or != 0. In the latter case, preemption is already disabled
+ * and no concurrency issues can occur.
+ *
+ * In the former case, we could be preempted just after reading the
+ * value 0 from memory, and a concurrent process might, in fact,
+ * bump the value of preempt_forbid_cnt under our nose!
+ *
+ * BUT: if this ever happens, then we won't get another chance to
+ * run until the other process calls proc_permit() to re-enable
+ * preemption. At this point, the value of preempt_forbid_cnt
+ * must be back to 0, and thus what we had originally read from
+ * memory happens to be valid.
+ *
+ * No matter how hard you think about it, and how complicated you
+ * make your scenario, the above holds true as long as
+ * "preempt_forbid_cnt != 0" means that no task switching is
+ * possible.
+ */
+ ++preempt_count;
+
+ /*
+ * Make sure preempt_count is flushed to memory so the preemption
+ * softirq will see the correct value from now on.
+ */
+ MEMORY_BARRIER;
+ }
+
+ /**
+ * Re-enable preemptive task switching.
+ *
+ * \sa proc_forbid()
+ */
+ INLINE void proc_permit(void)
+ {
+ extern cpu_atomic_t preempt_count;
/*
* This is to ensure any global state changed by the process gets
* flushed to memory before task switching is re-enabled.
*/
MEMORY_BARRIER;
-
/* No need to protect against interrupts here. */
- extern int preempt_forbid_cnt;
- --preempt_forbid_cnt;
- ASSERT(preempt_forbid_cnt >= 0);
-
+ ASSERT(preempt_count > 0);
+ --preempt_count;
/*
- * This ensures preempt_forbid_cnt is flushed to memory immediately
- * so the preemption interrupt sees the correct value.
+ * This ensures preempt_count is flushed to memory immediately so the
+ * preemption interrupt sees the correct value.
*/
MEMORY_BARRIER;
+ }
- #endif
-}
+ /**
+ * \return true if preemptive task switching is allowed.
+ * \note This accessor is needed because preempt_count
+ * must be absoultely private.
+ */
+ INLINE bool proc_preemptAllowed(void)
+ {
+ extern cpu_atomic_t preempt_count;
+ return (preempt_count == 0);
+ }
+#else /* CONFIG_KERN_PREEMPT */
+ #define proc_forbid() /* NOP */
+ #define proc_permit() /* NOP */
+ #define proc_preemptAllowed() (true)
+#endif /* CONFIG_KERN_PREEMPT */
+/** Deprecated, use the proc_preemptAllowed() macro. */
+#define proc_allowed() proc_preemptAllowed()
/**
* Execute a block of \a CODE atomically with respect to task scheduling.
proc_permit(); \
} while(0)
-#ifndef CONFIG_KERN_MINSTACKSIZE
+/**
+ * Default stack size for each thread, in bytes.
+ *
+ * The goal here is to allow a minimal task to save all of its
+ * registers twice, plus push a maximum of 32 variables on the
+ * stack. We add also struct Process size since we save it into the process'
+ * stack.
+ *
+ * The actual size computed by the default formula greatly depends on what
+ * options are active and on the architecture.
+ *
+ * Note that on most 16bit architectures, interrupts will also
+ * run on the stack of the currently running process. Nested
+ * interrupts will greatly increases the amount of stack space
+ * required per process. Use irqmanager to minimize stack
+ * usage.
+ */
- #if (ARCH & ARCH_EMUL)
- /* We need a large stack because system libraries are bloated */
- #define CONFIG_KERN_MINSTACKSIZE 65536
- #else
- /**
- * Default stack size for each thread, in bytes.
- *
- * The goal here is to allow a minimal task to save all of its
- * registers twice, plus push a maximum of 32 variables on the
- * stack.
- *
- * The actual size computed by the default formula is:
- * AVR: 102
- * i386: 156
- * ARM: 164
- * x86_64: 184
+#if (ARCH & ARCH_EMUL)
+ /* We need a large stack because system libraries are bloated */
+ #define KERN_MINSTACKSIZE 65536
+#else
+ #if CONFIG_KERN_PREEMPT
+ /*
+ * A preemptible kernel needs a larger stack compared to the
+ * cooperative case. A task can be interrupted anytime in each
+ * node of the call graph, at any level of depth. This may
+ * result in a higher stack consumption, to call the ISR, save
+ * the current user context and to execute the kernel
+ * preemption routines implemented as ISR prologue and
+ * epilogue. All these calls are nested into the process stack.
*
- * Note that on most 16bit architectures, interrupts will also
- * run on the stack of the currently running process. Nested
- * interrupts will greatly increases the amount of stack space
- * required per process. Use irqmanager to minimize stack
- * usage.
+ * So, to reduce the risk of stack overflow/underflow problems
+ * add a x2 to the portion stack reserved to the user process.
*/
- #define CONFIG_KERN_MINSTACKSIZE \
- (CPU_SAVED_REGS_CNT * 2 * sizeof(cpustack_t) \
- + 32 * sizeof(int))
- #endif
+ #define KERN_MINSTACKSIZE \
+ (sizeof(Process) + CPU_SAVED_REGS_CNT * 2 * sizeof(cpu_stack_t) \
+ + 32 * sizeof(int) * 2)
+ #else
+ #define KERN_MINSTACKSIZE \
+ (sizeof(Process) + CPU_SAVED_REGS_CNT * 2 * sizeof(cpu_stack_t) \
+ + 32 * sizeof(int))
+ #endif /* CONFIG_KERN_PREEMPT */
+
#endif
-#define CONFIG_PROC_DEFSTACKSIZE CONFIG_KERN_MINSTACKSIZE // OBSOLETE
+#ifndef CONFIG_KERN_MINSTACKSIZE
+ /* For backward compatibility */
+ #define CONFIG_KERN_MINSTACKSIZE KERN_MINSTACKSIZE
+#else
+ #warning FIXME: This macro is deprecated, use KERN_MINSTACKSIZE instead
+#endif
+
+/**
+ * Utility macro to allocate a stack of size \a size.
+ *
+ * This macro define a static stack for one process and do
+ * check if given stack size is enough to run process.
+ * \note If you plan to use kprintf() and similar functions, you will need
+ * at least KERN_MINSTACKSIZE * 2 bytes.
+ *
+ * \param name Variable name for the stack.
+ * \param size Stack size in bytes. It must be at least KERN_MINSTACKSIZE.
+ */
+#define PROC_DEFINE_STACK(name, size) \
+ cpu_stack_t name[((size) + sizeof(cpu_stack_t) - 1) / sizeof(cpu_stack_t)]; \
+ STATIC_ASSERT((size) >= KERN_MINSTACKSIZE);
/* Memory fill codes to help debugging */
#if CONFIG_KERN_MONITOR
#include <cpu/types.h>
#if (SIZEOF_CPUSTACK_T == 1)
- /* 8bit cpustack_t */
+ /* 8bit cpu_stack_t */
#define CONFIG_KERN_STACKFILLCODE 0xA5
#define CONFIG_KERN_MEMFILLCODE 0xDB
#elif (SIZEOF_CPUSTACK_T == 2)
- /* 16bit cpustack_t */
+ /* 16bit cpu_stack_t */
#define CONFIG_KERN_STACKFILLCODE 0xA5A5
#define CONFIG_KERN_MEMFILLCODE 0xDBDB
#elif (SIZEOF_CPUSTACK_T == 4)
- /* 32bit cpustack_t */
+ /* 32bit cpu_stack_t */
#define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5UL
#define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBUL
#elif (SIZEOF_CPUSTACK_T == 8)
- /* 64bit cpustack_t */
+ /* 64bit cpu_stack_t */
#define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5A5A5A5A5ULL
#define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBDBDBDBDBULL
#else
- #error No cpustack_t size supported!
+ #error No cpu_stack_t size supported!
#endif
#endif
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